UTAH ACADEMY OF SCIENCES 35 
These lithological characters I have found to be co- 
extensive with the Jurassic of Southeastern Utah. Whether 
or not they exist in other localities of our State only time 
and research will reveal. But in the absence of paleonto- 
logic evidence, I believe the above division will serve for 
the: present purpose, as I shall not try to correlate the 
several series with those known from other sections of the 
United States. For the solving of a problem of such 
moment, the fauna so far collected is too meager. I shall 
have occassion to speak of this phase later. 
From our present knowledge of the distribution and 
faunal relations in this Western Interior Region, it is highly 
probable that the strata were laid down in a narrow em- 
bayment of the Northern Pacific Ocean. It also appears 
that near the beginning of the Middle Jurassic this em- 
bayment was broken up into many lagoons. 
From the character of the Lower Jurassic strata in 
Utah, it appears that we had to do with a comparatively 
shallow bay. This may be accounted for by the fact that 
this region was at the extreme southern end of the embay- 
ment. The subsidence and deposition must have proceeded 
apace, as evidenced by the even graining of the lower mas- 
sive 500 feet of the Jurassic Sandstone. . 
The next 500 feet changes greatly in character. One 
of two things took place; either the deposition became 
greater than the subsidence or a slight rise occurred. Asa 
result the succeeding sedimentation was brought within 
the sphere of activity of currents and eddies, and the second 
500 feet of the Jurassic Sandstone is characteristically 
cross-bedded. 
During the time necessary for the deposition of this 
one thousand six feet of sandstone, the conditions were 
remarkably uniform. There were few and slight oscillations 
with no orogenic movements. The period seems to have 
been one of repose. However the conditions were not 
favorable to the sustenance of life. I have searched dili- 
gently for any evidence of a flora or fauna in this extensive 
sandstone, but have been rewarded with negative results. 
The end of the Lower Jurassic is marked by sudden 
subsidence and the Middle Jurassic first makes its ap- 
